What is diabetic neuropathy? Why does diabetes cause nerve pain?

Diabetes mellitus has become one of the commonest chronic medical conditions affecting people everywhere today. Unfortunately, diabetes is associated with several possible medical ‘complications’. One of these complications is damage to nerves called ‘neuropathy’ (neuro=nerves, pathy=disorder). Neuropathy can often be prevented, delayed and even controlled with good blood glucose control. However, when severe, special treatments are required to help with the symptoms of neuropathy.

This article will first discuss the normal role of nerves in the body. Then we will see what happens when nerves malfunction. This will be followed by a discussion of how and why nerves get damaged in diabetes. You can also find detailed articles about various treatments for neuropathy by browsing this website.

What is the normal function of nerves in the body?
The human body is very complex. Just for the purpose of this discussion, let us compare a robot to the human body (the human body is far more complex and sophisticated than a robot, but we are making this example just for learning and understanding reasons, so please do not be offended by this comparison). This robot’s name is Su-man. There is a central super-computer that controls Su-man’s every function and movement. There are wires that runs between this super-computer and every other part of Su-man’s body: its arms, legs, eye-cameras, etc. Su-man is a very advanced robot. If something bumps into it or someone touches it, that sensation is carried by special ‘sensory’ (sensation) wires to the super-computer in its head. There are also different wires that run from the brain to Su-man’s arms and legs that can tell the arms and legs to move so that Su-man can run away or defend itself from danger. These wires are called ‘motor’ (movement-controlling) wires.

As you guessed, in the case of the human body, the super-computer is the brain. The ‘sensory wires’ that carry sensations like touch, temperature, position of an arm or leg in space, etc are called ‘sensory nerves” which run from the arms, legs, and other parts of the body to the brain. The ‘motor wires’ are that carry instructions from the brain to the arms and legs telling them to move, are called ‘motor nerves’. There are other types of nerves too which carry information to the brain, or instructions from the brain that help control functions like sweating, blood circulation, hormones release, digestion, sexual function, urination, bowel or stool movement, etc.

What happens when nerves are damaged in the body? What are the symptoms of diabetic neuropathy?
As you have seen in the paragraph above, different types of nerves help control body function. Certain nerves carry sensations like touch, temperature, and position of an arm or leg in space. When these ‘sensory’ nerves are affected or damaged, the effects can be numbness, tingling, incoordination, clumsiness, increased risk of falls and bumping into things. Damage to these nerves can also alter the sensation being carried by these nerves. So for example, instead of carrying light touch sensation from the feet to the brain, the damaged nerves carry wrong signals to the brain which make that sensation feel like pain instead of touch. This is the reason why some people with diabetes find it so painful to wear socks, or even have a bed sheet touch their feet.

Similarly, when nerves carrying movement or motor signals to muscles get damaged, the effects are weakness in the feet, legs, hands or arms. This can affect functions like writing, lifting, standing, walking, etc.

Diabetic neuropathy can also affect nerves which help coordinate other functions in the body like nerves that help control blood circulation, hormones release, digestion, sexual function, urination, bowel or stool movement, etc. For example, diabetic neuropathy can affect the nerves controlling vision, which can cause blurring of vision. When severe, loss of vision can occur, but this can often be prevented by following the Preventive measures discussed elsewhere in this website. When diabetic neuropathy affects the stomach, it is often called diabetic gastroparesis. There is slowing of stomach emptying, and effects on digestion and intestine function.

How and why does diabetes damage nerves in the body?
The exact reason for damage to nerves due to diabetes has never been proven. What scientists and medical research have proven is that there is a direct relationship between high blood glucose and neuropathy. This means that medical research has shown that people who have high blood glucose levels tend to develop neuropathy earlier and to a more severe degree than people who have closer to normal levels of blood glucose. When the blood glucose is better controlled or brought closer to normal, the effects of neuropathy decrease and there is also less spread or worsening of neuropathy. This implies that it is either the higher than normal blood glucose itself, or certain chemicals in the body affected by high blood glucose that cause the damage to nerves in the body. It is also known that diabetes affects blood circulation in the body. Nerves need nourishment from blood just like most other organs and parts of the body. Very tiny blood vessels carry blood to the various nerves in the body. Poorly controlled diabetes can cause narrowing of these blood vessels affecting the blood supply to the various nerves. When nerves do not receive adequate blood supply, they start to malfunction.

We hope this article was helpful in understanding the normal function of nerves in the body, how diabetes affects nerves, and answered your question “What is diabetic neuropathy.” For additional information about symptoms, how to prevent or better control neuropathy symptoms, diagnosis, reviews of various treatments and options, please browse the other topics and articles on this website. Thank you for reading.